Like most beaver trappers, nothing makes my heart flutter faster than seeing a large lump of brown fur floating next to my set location.

And for me, the satisfaction quadruples when I reel in my trap chain to find an adult flattail at the business end. Not only do I know that I just added a valuable pelt to my fur harvest, but the sheer size of an adult beaver always makes me gasp in disbelief.

So far, my largest beaver weighed 66 pounds. In fact, I have caught two that scaled 66, and several more that topped 60 pounds.

The largest beavers I have ever seen were trapped by Tom Olson in northern Minnesota — a couple of behemoths that weighed more than 70 pounds. They were impressive rodents, without question.

However, by Ice Age standards, a 70-pound beaver was little more than a baby.

The giant beaver (Castoroides ohioensis), a cousin to our modern-day North American beavers, grew to 8 feet long, stood more than 3 feet high and weighed up to 500 pounds!

According to C.R. Harrington of the Canadian Museum of Nature, giant beavers ranged from Florida to the Yukon, but no evidence of them has been found outside of North America.

Judging by fossil discoveries, they seem to have been most common in the southern Great Lakes region. Three nearly complete specimens were found in Indiana and Minnesota.

The skeletal similarities between giant beavers and the beavers we trap today leads paleontologists to believe that giant beavers — except for their truly mammoth size — had a similar appearance to modern flattails.

However, giant beavers had cutting teeth up to 6 inches long with ridged outer surfaces. In addition, giant beavers’ tails were narrower in relation to length, and their hind legs were relatively short.

“Considering the great weight of the animals, their ability to disperse overland as some living beavers do would have been reduced,” Harrington wrote.

The inability to migrate when prolonged drought hit might have led to the extinction of giant beavers, which are believed to have died out about 10,000 years ago.

Giant beavers are thought to have lived more like muskrats than today’s beavers, preferring to eat cattails and other soft vegetation rather than tree bark. Also, giant beavers might not have been skilled dam builders, possibly because their teeth were not as well adapted to chop trees.

Researchers think giant beavers had poor eyesight just like today’s beavers, but a much better sense of smell.

Castoroides ohioensis are not a direct ancestor of Castor canadensis, our modern North American beavers. In fact, fossil evidence shows the species co-existed at the end of the last Ice Age.

Interestingly, early humans also inhabited North America before giant beavers vanished.

Can you imagine the size of bodygrip trap necessary to catch a 500-pound beaver?